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1985 90 hp Johnson

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sforce1218

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Hope someone can help just purchased a boat with a 90 hp johnson VRO V4 it used to have a oil tank but no longer there, have been mixing the gas and oil here is the question do i need to remove the oil pump and do i need to do any thing to the carbs, motor runs ruff and sucks down the fuel any help for the new guy ??
 
The VRO pump can be used to pump mixed fuel no problem ( bypassing the oil mixing side of the pump ) and a pre 83 pump is a simpler cheaper alternative..-------------I have about 10 or more of these motors apart at the moment , all have suffered from broken piston rings.--------------So do a compression test to determine the overall health of the motor.-------------These motors can put away a lot of fuel at full throttle , so how much is it using ???
 
Thanks for any help I disconnected the wires from the pump today do i need to do anything else, as far as how much fuel is uses i have run it 4 times now and as far i can tell we have gone about 5 to 7 miles on 5 gal of fuel and not all was full out seems a little much to me.
 
I just done a comp check looking at the back of the motor left side is at about 115 and right is about 105 and how to [ bypassing the oil mixing side of the pump] just downloaded the manual for the motor.
Thanks for any help
 
Plug the hose that feeds oil to the pump.-----------Plug it near the pump.-----Remove cover in front of carburetors , operate the manual fuel pump and see if there is any leakage.-------------------The distance you travelled is not relevant to mileage !!!------------How many gallons / hour is relevant and means something.
 
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Thanks The hose is plugged were the fuel enters the motor i will plug them near the pump---- is the compression ok --- On the water from 8am till 4pm jumping from place to plane 45min to 1hr at any place full throttle for about 45 min to 1 hr at most. Thanks again
 
6 gallons / hr is not bad !!-------Compression is not great but ??-----------------Typically on those with a broken ring problem you will see 100 or so and then a couple of cylinders at 20/30 psi.
 
Thanks for all the help. Just rebuilt the carbs and cleaned the fuel system Can i replace the fuel pump with a electric pump with a fuel regulator if so what should the psi be to the carbs.
 
Don't think so. Get a smaller motor or a 4stroke to save gas.
90hp with VRO wires disconnected, plugged oil hose to motor, carbs serviced, no gas leak and 105lbs to 115lbs compression is just about right at that burning rate. A little rough - yes- because of the compression difference between one bank to another. Don't run on old spark plugs either.
I used to have a 70hp Merc that burnt 6gal in 30minutes.
 
Near the starter on the intake manifold..---------------If you have the pump and gasket " in hand " , then it will all become simple.
 
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